Oxidation cyclohexene-4,5-dicarboxylic

Figure 11.30 Reaction scheme for the oxidation of cyclohexene dicarboxylate (after [122]).

The epoxidation method developed by Noyori was subsequently applied to the direct formation of dicarboxylic acids from olefins [55], Cyclohexene was oxidized to adipic acid in 93% yield with the tungstate/ammonium bisulfate system and 4 equivalents of hydrogen peroxide. The selectivity problem associated with the Noyori method was circumvented to a certain degree by the improvements introduced by Jacobs and coworkers [56]. Additional amounts of (aminomethyl)phos-phonic acid and Na2W04 were introduced into the standard catalytic mixture, and the pH of the reaction media was adjusted to 4.2-5 with aqueous NaOH. These changes allowed for the formation of epoxides from ot-pinene, 1 -phenyl- 1-cyclohex-ene, and indene, with high levels of conversion and good selectivity (Scheme 6.3). 

Cyclohexene-1,2-dicarboxylic ANHYDRIDE, cis-, 30, 93 Cyclohexene oxide, 32, 39, 40 Cyclohexene sulfide, 32, 39... 

Protons present in aqueous acid also act as reasonably efficient electron acceptors. If the reduced hydrogen atoms are formed on metallized suspensions, catalytic hydrogenation can result. For example, in contrast to the oxidative chemistry reported earlier for cyclohexene-4,5-bis-dicarboxylic acid (Eq. 28), if the reaction is conducted in the absence of oxygen in aqueous nitric acid, catalytic hydrogenation of the double bond becomes a major pathway, Eq. (34). ... 

Cyclohexene-1-acetonitrile, 31, 25, 26 4-Cyclohexene-1, 2-dicarboxylic ACID, DIETHYL ester, cis-, 30, 29 4-Cyclohexene-1,2-dicarboxylic ANHYDRIDE, cis-, 30, 93 Cyclohexene oxide, 32, 39, 40 Cyclohexene sulfide, 32, 39... 

In contrast to 1,2-dimethylcyclohexene, methyl cyclohexene-1,2-dicarboxylate was reported to yield only the cis saturated product in the hydrogenation over platinum oxide in acetic acid at 26-27°C, independently of the pressure of hydrogen (0.1-20 MPa) and the concentration of the substrate (0.05-1,0M).140 Hydrogenation of methyl cyclohexene-1,6-dicarboxylate also gave the same result at about 1 atm H2, but some of the trans isomer (6+2%) was formed at a pressure of 13 MPa H2. 

Zn(Mn04)2 effects several known oxidations such as oxidation of alkynes to a-diketones, cyclic ethers to lactones, and cycloalkanones to dicarboxylic acids. The paper reports one novel transformation Oxidation of a cyclohexene to a ketol in moderate yield (36%), equation (I). 

Draw the three-dimensional structures of the following, indicating the interactions that may exist (a) -butane in its staggered form (b) -butane in its eclipsed form about the 2,3-bond (c) 1,2-dibromoethane in its most stable form (d) cyclopropane (e) 1,2-epoxyethane (ethylene oxide) showing the lone pairs of electrons on the oxygen (f) cis- and rart.v-1,4-dimethylcyclohexane in the chair form (g) /ran.v-cyclohexane-l,2-dicarboxylic acid (h) cyclohexene. 

The oxidation of alkenes and cycloalkenes and their halogen derivatives with at least one hydrogen or halogen atom at the double bond leads to carboxylic acids. Ozonolysis usually requires the oxidative decomposition of the ozonide. The oxygen content of the ozonide is not sufficient for the formation of two molecules of acids or one dicarboxylic acid. The nonoxidative decomposition of cyclohexene ozonide gives an aldehyde-acid or its derivatives [1108]. It comes, therefore, as a surprise that carboxylic acids are claimed as products of the decomposition of ozonides by hydrogenation over the Lindlar catalyst [55] (equation 108). 

In contrast with the results obtained with simple allqfl halides, benzyl bromide leads to the formation of 77 and the ketone 78 in variable ratios (Scheme 26). A similar result has been reported in the reactions between the oxidative addition product of Ni(COD)bpy or Ni(COD)TMEDA with cw-4-cyclohexen-l,2-dicarboxylic anhydride and alkyl iodidesWith allyl bromide as the electrophile, ketone 79 is the only product isolated. However, when the reaction is performed with isolated nickelacycle 66 in the absence of Ni(CO)2Me2Phen, allylated alanine 80 is formed exclusively (60% yield) (Scheme 26). These results show that the carbonyl nickel complex is not inert because with certain reagents it transfers CO to the nickeMactone 66. Alternatively, the formation of ketones in these reactions could be explained by alkylation of the primary oxidative addition product or by carbonylation of allyl or benzyl bromide to give acyl bromides which react with 66 to give the observed products. However, this last reaction pathway seems unlikely because acetyl or benzoyl chloride do not react with in situ generated nickelacycle 66. 

This disconnection suggests that 147 is prepared by enolate alkylation of cyclopentanone (Section 22.9). If a Dieckmann condensation is planned, the precursor to cyclopentanone is 148, which in turn is derived from diester 149. Another ester may be chosen at this point (methyl, etc.). Diester 149 is derived from the dicarboxylic acid, which is prepared by oxidative cleavage (ozonolysis) of cyclohexene. Bromocyclohexane 146 is now the clear precursor to cyclohexene by an E2 reaction (Chapter 12, Section 12.1). 

As a result, two composite systems derived from partially aliphatic polyimides— 5-(2,5-dioxotetra-hydrofurfuryl)-3-methyl-3-cyclohexene-l,2-dicarboxylic acid anhydride reacting with 4,4 -oxydianiline (DOCDA-ODA) and with iron oxide as Fe304—were prepared at different temperatures, 250 and 300°C (Nica et al. 2015). Correlations among the structural, morphological, thermal, and magnetic properties were established for possible application as humidity sensor devices. In addition, the influence of humidity on the electrical properties of poly(DOCDA-ODA)/iron oxide composite were discussed, which led to an analysis of the humidity sensitivity of pure polyimide and of a poly(DOCDA-ODA)/Fe304 with different filler contents of iron oxides at various values of relative humidity (RH). 

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